Conveyor systems are known which comprise a series of mobile conveyors. Each mobile conveyor has an inclined belt or the like. The material being conveyed is lifted by each conveyor in turn and dumped from its upper end onto the next conveyor of the series.
The main advantage of such systems is that they are flexible in operation. For example, if in a harbour a ship carrying grain must be off-loaded at a quay not usually used for that purpose, mobile conveyors can be strung out from the ship to the storage place. As soon as the ship is unloaded, the conveyors can be taken away for use elsewhere. Fixed conveyor systems on the other hand tend to be inflexible. They can convey material from a fixed loading point to a fixed discharge point but cannot be moved to cater for unexpected materials handling requirements.
Known conveyor systems are electrically driven, each mobile conveyor having its own electric motor. Power cables are run from the motors to one or more supply and control points. Often there is a single supply and control point and a multitude of cables running from it to the motors of the mobile conveyors. The multitude of cables adds to the cost of the system. Furthermore the large number of cables that have to be run from the control point to the motors form obstructions and potential danger points.
Control of all the conveyor motors is exercised from the single supply and control point. Hence, in an emergency, someone must reach or get a message to the single supply and control point to get the system switched-off.